How does Jin's side effect even work it is a mystery I have given up on orz

As rays of sun sneak their way through the gaps in the curtain, Jin opens his eyes. He fell asleep in his Border uniform again. He lurches out of bed, half stumbling over the blanket before kicking it out of the way. Jin checks his cellphone as he closes the door of his room behind him; his timing is as impeccable as always, the bathroom should be empty by now.

The mirror over the sink is still slightly fogged from use, but the room itself is as empty as he had seen. Jin does not wipe the condensation off until he finished his ablutions. He tries a smile. In the mirror, futures bloom and fade; he is crying, he is smiling, he is eating some really good ramen.

There is an empty chill in the corridors of Tamakoma, an echoing silence broken only by the scuff of his shoes. It doesn't last; once he's close enough to the kitchen, he can hear a familiar rhythmical thock-thock-thock. Reiji is at the kitchen counter, arms bulging attractively with a kitchen knife. Jin grabs a chair and takes a seat on the other side of the counter, arms crossed over the tall back. He rests his head on top and lets the cosy sound of chopping fill him up.

"There are some leftovers in the fridge," Reiji says without turning around. "Want me to warm something up for you?"

"That's okay," Jin says breezily, watching Reiji as he works. Reiji in his trion body, Reiji in a suit, Reiji in a funeral kimono. Indefinite futures that waver and vanish from his consciousness, except the last. That is a future that awaits everyone, the only thing that changes is the number of wrinkles on the resting face. "I'll do it myself in a little bit. What are you making?"

Reiji grunts, finally turning around to look at Jin. "There was a sale at the supermarket Kyousuke works at; he brought over some extras yesterday." He waves at a truly incredible pile of cabbages off to the side. "My shift finished early today anyway, so I thought I'd make cabbage rolls for tonight and use them all up."

"That's going to be a lot of cabbage rolls." Jin eyes the pile.

"I was thinking of inviting Kazama, and with all of Tamakoma branch here tonight it should be enough." Reiji stops chopping to look at Jin again. "If you're going to be here tonight. You were out all last night. I'm actually a bit surprised you woke up before dinnertime considering when you went to bed."

Jin hums thoughtfully. "I think I'll be Tachikawa-san's tonight. But I can take some cabbage rolls over with me. It'll be better than going out to eat."

"Good. The two of you need more home-cooked meals." Reiji puts down the knife, turning so that he's facing Jin fully. "How is it going? You look pretty exasperated for a guy talking about going to his boyfriend's house."

"That's the problem I think," Jin sighs. "He's treating me like one of his girlfriends!"

Reiji snorts. "Now that's a face I don't usually see on you."

Jin groans, burying his head in his crossed arms.

"I'm listening if you want," Reiji offers easily, not a hint of judgement in his manner. That's Reiji-san for you.

Jin raises his head a little, just enough that he can barely make out Reiji's silhouette above his arms. Reiji's blurry silhouette, filtered through Jin's lowered eyelashes. In contrast, the view of Reiji in his funeral kimono is clear enough for Jin to count the number of wrinkles as they wink in and out of view.

"Why do you think he treats you like one of his girlfriends anyway? I didn't notice him acting any differently from normal."

"Most of the time, Tachikawa-san is just Tachikawa-san," Jin admits, "but it's different when we have sex." Jin takes in the look on Reiji's face. "You asked."

"I did." Reiji sighs. "Don't go into specifics."

"Well, I wasn't really going to," Jin says drily. He slides his eyes away from Reiji. "Tachikawa-san's always fighting something, you know? And he always looks like he has so much fun doing it. It's really cool."

Reiji grunts noncommittally, not shifting an inch.

Jin continues, "Obviously I knew that things will change if sex gets involved. I guess…I just wasn't expecting him to treat me like a different person." Jin groans. "Wow I never thought I would every have to say that about Tachikawa-san."

"Some people don't see sex as fighting," Reiji points out.

"We're rivals," Jin says, offended.

"Do you want to be rivals or do you want to be lovers?" Reiji asks.

Jin makes a face. "I'm not explaining myself very well."

"It isn't me you have to convince. It's yourself. And Tachikawa." Reiji shrugs.

"Yeah," Jin concedes, shifting in his seat. "I don't think this is what Tachikawa-san wants either. Not- I mean, it isn't the sex. I don't think either of us regrets any of this. But I don't think either of us knows how to treat each other as something other than rivals either. So Tachikawa-san took the easy way out; treating me like a stranger. One of the women he used to woo and then get dumped by."

Reiji gives him a steady look. "What are you going to do about it?"

Jin scowls. "Why do I have to do something about it anyway? Tachikawa-san is the one's acting stupid."

"So your plan is to wait until Tachikawa figures it out. Whatever 'it' is."

"I know how that sounds." Jin narrows his eyes at his reflection in the steel furnishings. "But it's not that bad a plan. My side effect tells me so."

Reiji huffs in amusement. "Well, it's good for you to be a little indulgent now and then."

"And what's that supposed to mean?" Jin pouts exaggeratedly at him. "I'm very indulgent. I always indulge."

"Uh-huh." Reiji nods distractedly, turning back to the chopping board.

Jin sniffs, then slides off the chair when it doesn't look like Reiji is paying attention to him anymore. He makes his way to the fridge, fishing out one of the neatly packaged containers. He catches his reflection blinking up at him from a metal bowl as he closes the door. The future moves. "Huh."

Jin did not tell Reiji everything; which is just as well, because he doesn't think either of them really wants a conversation about Jin using his side effect during sex – or not using it in this case. But it's just a big a problem as the fact that Jin refuses to give any hints as Tachikawa stumbles around fruitlessly trying to make a relationship with his enemy. Bigger, maybe, because this is what it comes down to in the end: Tachikawa's uncertainty and Jin's passivity; Jin refusing to let him in, refusing to let him try to overturn Jin's foresight when he's never refused him that right before.

It is almost a relief that Tachikawa does not let that stand. That he fights his way inside Jin's defences, makes Jin look at him instead of turning away. Because Tachikawa is at his best, his brightest, when he fights. Relief and guilt, because Tachikawa shouldn't have to guess Jin's wants like this, it is on Jin to tell him. But Jin is selfish; if you give him an inch he will take the mile. Reiji doesn't know how right he was to say that Jin was being indulged.

"Look at me," Tachikawa says, covering Jin with his whole body so that he is surrounded on all sides. As if Jin can see anything else.

"Tachikawa-san." Jin can feel Tachikawa moving inside him, an undeniable anchor that moors him to the present. In front of his eyes, Tachikawa is smiling down at him naked as the day he was born, Tachikawa is swinging his Kogetsu in a swirl of his longcoat, Tachikawa with his mouth full of mochi. And, as always, the future in which Tachikawa is dead. But today that future is a distant thing.